Materia medica​, the materials of medicine - the herbs, is one of the two primary subjects covered in the herbal apprenticeship. The other subject is diagnosis. Assessment of the pulse, tongue, abdomen (hara)... etc. brings us to an understanding of the energetic condition in question. In holistic medicine, many variables are considered. Regarding the selection of herbs, the condition or pattern presenting itself indicates a certain category of the materia medica, which is, of course, arranged by therapeutic categories of clinical significance. So, herbalism is a combining of these two primary aspects: diagnosis and materia medica. The study of materia medica extends into particulars about each herb, the art of formulating, herb preparation, and many other details, but it must start with the herbs. Our herbal apprenticeship materia medica list was first arranged according to Michael Tierra's Planetary Herbology and has since been added to using Dan Bensky's and Andrew Gamble's Chinese Herbal Medicine Materia Medica.